The Transient Nematic Liquid Crystal Modulator As An Active Q-Switch For Solid State Lasers

Recently, fast electro-optical switching in planar nematic liquid crystals using multipass and also Fabry-Perot modulators has been reported. By applying short driving-voltage pulses of 150V microsecond switching times have been achieved with nematic planar cells (NPC) and even sub-microsecond switching in case of nematic Fabry-Perot modulators (NFPM). In the present report the performance of these modulators depending on the thickness, the temperature the amplitude and the width of driving pulsed voltage is discussed with respect to realization of nematic Q-switch modulators for solid state lasers. A special ITO-electrode configuration has been developed to minimize the electrical time constant of the modulators. Results of using those fast nematic modulators as active Q-switches in flash lamp pumped Nd:YAG solid state lasers are shown. Three different resonator configurations have been designed. The realized Q-switch lasers emit pulses of 40-70 ns duration (FWHM) and energies between 10-25 mJ.